The present invention relates to a semiconductor device, and more particularly to a diffusion barrier layer for a semiconductor device and a fabrication method thereof which is stable even at a high temperature by combining an insulating material and a refractory metal.
A diffusion barrier layer in a semiconductor device delays diffusion or prevents a chemical reaction between an interconnection material and a substrate material or between interconnection materials. Therefore, a stable diffusion barrier layer is essential for the development of reliable semiconductor devices. Since it is almost impossible for the diffusion barrier layer to completely prevent the diffusion, the performance of the diffusion barrier layer depends upon how long the diffusion barrier layer can play its part under various annealing conditions. The diffusion barrier layer is required to have properties, such as being stable thermodynamically even when being in contact with the interconnection and the substrate material, having low contact resistance and excellent adhesivity, being tolerable to thermal and mechanical stress and having high electric conductivity. Further, it is desirable that a coefficient of thermal expansion of the diffusion barrier layer is similar to that of the substrate material.
Such diffusion barrier layer is mainly divided into a passive barrier, a sacrificial barrier and a stuffed barrier. More specifically, the passive barrier prevents the reaction with the interconnection and the substrate material by using a material which is thermodynamically stable and chemically inert. The sacrificial barrier layer reacts with the interconnection material or the substrate material, but the reaction is very slow. Thus, the sacrificial barrier layer serves as the diffusion barrier layer until it is exhausted due to the reaction with the interconnection material or the substrate material. Lastly, the stuffed barrier prevents the diffusion by filling other materials into grain boundaries that become the paths of the diffusion. Here, the diffusion barrier layer according to the present invention belongs to the stuffed barrier. As mentioned above, stuffing implies filling of other material into the grain boundaries.
Generally, the grain boundaries have been known as fast diffusion paths, since the diffusion along the grain boundaries occurs much more easily than through crystallites in a poly-crystalline thin film. Therefore, to prevent the diffusion along the grain boundaries, single crystal or material which has no grain boundary, or the stuffed film in which other materials are filled in the grain boundaries is used as conventional diffusion barrier layers. Among the conventional diffusion barrier layers, however, the amorphous diffusion barrier layer which is thermodynamically unstable is transformed into a crystalline structure and thus there exists grain boundaries.
As a fabrication method of the conventional stuffed barrier layer, there is a method for blocking the grain boundaries by precipitating into the grain boundaries a precipitation, or implanting a material into the grain boundaries by diffusing a impurity gas in the atmosphere. Most popular examples are nitrogen stuffing and oxygen stuffing. Particularly, the nitrogen stuffing is to precipitate nitrogen into grain boundaries by depositing a thin film which contains nitrogen in excess of its limit. The oxygen stuffing is to implant oxygen into the grain boundaries by performing the oxygen plasma treatment or annealing in oxygen atmosphere after thin film deposition. Using such implantation, nitrogen can be implanted.
However, in these methods, since nitrogen or oxygen is weakly bound with the matrix thin film, the stuffing effect becomes extinct when the annealing process is performed for a long time. Also, in implantation by using the plasma treatment, the thin film is damaged due to high ion energy, which results in bond break in the thin film and crystal defects such as dislocation, void and interstitial, etc.
Accordingly, the present invention is directed to a diffusion barrier layer and a fabrication method thereof that obviate the problems according to the related art.
An object of the present invention is to provide a diffusion barrier layer for a semiconductor device that is thermodynamically stable even at a high temperature and a fabrication method thereof.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, there is provided a diffusion barrier layer including an insulating material and a refractory metal, the insulating material being bonded to the refractory metal material and the diffusion barrier layer being in a microcrystalline or amorphous state.
Further, in order to achieve to the object of the present invention, there is provided a fabrication method of a diffusion barrier layer for a semiconductor device includes the steps of: forming a diffusion barrier layer containing a refractory metal material and an insulating material on an insulating layer and in a contact hole, wherein the insulating layer being partially etched to form the contact hole is formed on a semiconductor substrate; and annealing the diffusion barrier layer.
The foregoing and other objectives of the present invention will become more apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.